https://github.com/perazz/fastmath

A Modern Fortran library for fast, approximate math functions
https://github.com/perazz/fastmath

exponential fast-math fortran logarithm rsqrt

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A Modern Fortran library for fast, approximate math functions

• Host: GitHub
• URL: https://github.com/perazz/fastmath
• Owner: perazz
• License: mit
• Created: 2022-10-25T08:10:45.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2023-01-22T10:04:15.000Z (about 2 years ago)
• Last Synced: 2024-01-29T14:18:10.449Z (12 months ago)
• Topics: exponential, fast-math, fortran, logarithm, rsqrt
• Language: Fortran
• Homepage:
• Size: 12.7 KB
• Stars: 8
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# fastmath

This is a Modern Fortran library for fast, approximate math functions: `exp`, `log`, `1/sqrt`. 

These functions provide fast, approximate evaluations of the exponential, logarithm and normalization functions in 64-bit precision. 

A detailed explanation of the underlying math with the IEEE-754 representation is reported in ref [1].

For each function, a module is provided; the interface has both simple functions and a programmable object-oriented wrapper. 

References

==========

This code is released under MIT license; please cite the following reference whenever using it.

[1] F. Perini, R.D. Reitz, "Fast approximations of exponential and logarithm functions combined with efficient storage/retrieval for combustion kinetics calculations" Combustion and Flame 194(2018), 37-51. 

Building, using

===============

An automated build is not available yet. 

- `src/fast_exp.f90`   contains the exponential routines

- `src/fast_log.f90`   contains the logarithm routines

- `src/fast_rsqrt.f90` contains the 1/sqrt(x) routines.

- `test/test.f90` is the test driver program 

Each module has no external dependencies, they can also be used individually.

A simple command line build script is: 

```

gfortran src/fast_exp.f90 src/fast_log.f90 src/fast_rsqrt.f90 test/test.f90  -o fastmath_test.exe

```

A simple makefile for the GNU compiler suite is provided in folder `project`; to run it: 

```

cd project/

make -f makefile.gcc

```

The testing executable compares performance and accuracy wrt the compiler's intrinsics functions.